If you want good musical discovery, Pandora stands out from all the rest (e.g. for creating stations without vocals for work background). You have to work at it for a little while to craft your stations, but that is a discovery process too, about the qualities of the music you like.

If you want a social network, with music as the glue that holds it together, go with last-fm, or better yet, Jango. People who like these services put high importance on music as a shared experience.

I found Jango to be far easier than last-fm to figure out how to use, and it has one really interesting hook. At the bottom of the player there is a scrolling ribbon of like-minded users, along with the names of the songs and artists they are listening to. Click on the song and you can listen to it immediately; click on the user image and you go straight to their profile, where you can IM/email them.

Keeping users on the site and interacting with it is the key to advertising revenue, and perhaps survival, for this or any kind of site. If you have a well-crafted Pandora station, you might not even look at the web page for hours on end, right?

I did screencasts on both Pandora and Jango, for anyone who wants a quick primer on getting the most out of each service:

http://mainstream-guides.com/pandora
http://mainstream-guides.com/jango

If they come up with a pandora windows client or even better a sidebar gadget, I will never use anything else.

hmm… i wonder why they have it turned off in Europe!!! probably bandwidth cost.